The invention relates to a blade element for a refiner for refining fibrous material, the blade element comprising an inner edge and an outer edge, first blade bars and first blade grooves therebetween, the first blade bars and the first blade grooves extending toward the outer edge of the blade element, and at top surfaces of the first blade bars, second blade bars and second blade grooves therebetween, the second blade bars and the second blade grooves being at least partly transversal to the first blade bars, whereby the second blade bars and the second blade grooves alternate in a direction of the first blade bars.
The invention relates also to a refiner for refining fibrous material.
An example of the blade element as disclosed above is presented in WO-publication 2012/101331 A1.
A problem with these kind of blade elements is a higher wear rate of the blade bars in the vicinity of the outer edge than in the vicinity of the inner edge, which is originated from the higher circumferential speed in the vicinity of the outer edge than in the vicinity of the inner edge, because shearing forces, which affect on the wear rate of the blade bars, are dependent on the circumferential speed and a width of the blade gap between opposing refining elements of the refiner. The wear rate of the blade bars in the vicinity of the outer edge may be double to that in the vicinity of the inner edge. The higher wear rate in the vicinity of the outer edge may result in the blade bars in the vicinity of the inner edge to run into contact, causing fiber cutting and increased vibration levels in the refiner.